All things in all posts will help you visualize about the way that computers work generally. Note that it is not the real structure of modern computers, but the way that modern computers work is nearly the same as in my posts. I am sure that if you understand about the way that computers work in my posts, you will easy to learn about all fields of computer afterward. Thank you !!!
You knew about the memory bit in a computer in my previous post. With one memory bit, you can only save one state of one bit and you can not save many bit’s states concurrently. Because most information in computers need many memory bits to save, so you need a memory that is more than one bit. To do that, you need to connect many bits of memory together. In this post, I will show you a 8-bit memory that is for storing 8-bit information. As you know, one bit of memory will have an input “i” that represents the state of the bit that needs to be saved. An input “s” that decides whether the “i” input will be saved. And “o” output represents the state of the bit that was saved.
In the previous post, you also know about the diagram that we will use for one memory bit. We will use that diagram as building blocks to build larger structures such as 8-bit memory that we are examining. Now, look at another diagram below to understand structure of a 8-bit memory:
On the left of the picture, you can see a structure that is constructed from eight 1-bit memories. They are the same as the 1-bit memory diagram that we knew, but “s” inputs of them are connected together and they are also stacked to form a 8-bit memory. “i” input and “o” output are still separate for one bit in 8-bit memory.
On the right of the picture, you can see a structure that is the same as the 8-bit memory diagram on the left of the picture but it was simplified very much. Eight “i” inputs represent eight “i” inputs of eight 1-bit memory. Eight “o” outputs represent eight “o”outputs of eight 1-bit memory. “s” input is connected to every 1-bit memory so we only need one connection on the diagram to represent. The “B” letter is short for “Byte”. A 8-bit memory is called a byte. Sometimes, you will also see a 4-bit memory that is called a nibble.
Now, to represent information in one 8-bit memory, you need a 8-states string such as 0000 1111. You notice that we use “1” instead of “on” and “0” instead of “off” for the states of bits because it is common and maybe related to binary numbers (only have two digits: “0” and “1”). From top to bottom state of bits, you will convert them to from left to right state string. You can have a space every 4-bit for easy reading.
With n bits, we will have 2n combinations. This thing you may have learned at school. So with 2 bits, you can have two combinations: 0 1 and 1 0. With 3 bits, you can have 8 combinations: 0 0 1, 0 1 0, 1 0 0, 1 1 0, 1 0 1, 0 1 1, 0 0 0, 1 1 1. In the same way, you can have 16 combinations with 4 bits. And with 8-bit memory in this post, you can have 28 = 256 combinations of 8-bit states.
With each state of 8-bit memory, you can assign it with specific meaning. So we can have 256 meanings for an 8-bit memory. In the next post, we will learn the way these 256 combinations can be used in computers. It is really interesting. Thanks for reading and see you later.
0 Nhận xét